This invention relates to the field of position sensor error and, more particularly, to a self-correcting sensing circuit for throttle position sensing in a fuel injection system.
In fuel injection control systems, one very important input signal is a measure of throttle position since it is an indication of driver demand. An accurate measure of throttle position is necessary for the correct calculation of both fuel delivery and spark advance. In some systems, the calculations of fuel injection quantity and the like are divided into defined groups, with "closed throttle" being one such group, "nearly-closed" being another group, and more open throttle being another. Since the system requirements in the closed throttle position are substantially different from the requirement of the nearly-closed, it is critical to have an accurate measurement of throttle position. If the position sensor is slightly misplaced, due to either manufacturing tolerances or to a subsequent misadjustment as from vibration, serious errors in control signals may occur. This mispositioning of the sensor may cause a reading that is either too high or too low with respect to the correct value, and the difference between the actual and correct readings may be interpreted as an error signal. It is also desirable to use this error signal to compensate the actual signal to bring it to its correct value. At the same time an alert signal may be provided indicating that service to the device is required if the error signal exceeds a predefined limit.